Instead, police said she brought her 4-year-old son along for the heist.

The robbery occurred at approximately 5:30 p.m. Sunday, when the woman took her son inside the Old Navy store in the Willows Shopping Center at 1975 Diamond Boulevard, police said. An initial investigation revealed that the woman took several items, concealed them and fled the store without paying, police said.

A security officer followed the woman out of the store, where she pulled a knife and waved it at the security officer, all with her preschool-aged son in tow, police said.

After brandishing the knife, the woman escaped in a waiting car driven by a 40-year-old Bay Point woman, police said. Concord police found the vehicle within minutes, Lt. Tim Runyon said, and found the knife and stolen property in the vehicle, along with the 4-year-old.

Both women were arrested on suspicion of robbery, commercial burglary and child endangerment, police said, and also are expected to be charged in connection with a similar robbery at Fry's Electronics in the 1600 block of Willow Pass Road on Saturday. Neither was identified by police.

The 4-year-old was released by police to a relative and Children and Family Services were notified, police said.